Method for manufacturing liquid crystal display device with scribing groove

ABSTRACT

It is an object to prevent disordered orientation of liquid crystal molecules which is due to division of substrates even when a liquid crystal dripping method is used, and to provide a method for manufacturing a liquid crystal display device in which liquid crystal is not adversely affected even when a sealant not cured and liquid crystal are in contact. In a method for manufacturing a liquid crystal display device using a liquid crystal dripping method, a scribe groove is provided for at least one of a pair of substrates with a diamond cutter or the like before the pair of substrates are attached under reduced pressure. After the scribing, the pair of substrates are attached under reduced pressure, heat treatment for curing the sealant and aligning the liquid crystal molecules is performed, and the substrates are divided by applying impact using a breaking apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a liquidcrystal display device. For example, the present invention relates to amethod for manufacturing an electro-optical device typified by a liquidcrystal display panel having a circuit using a thin film transistor(hereinafter, a TFT) and a method for manufacturing an electronic deviceprovided with such an electro-optical device as a component.

2. Description of the Related Art

In recent years, attention has focused on a technique for forming a thinfilm transistor (TFT) by using a semiconductor thin film (having athickness of approximately several nanometers to several hundreds ofnanometers) formed over a substrate having an insulating surface. Thinfilm transistors are widely applied to electronic devices such as ICsand electro-optical devices, and in particular, their rapid developmentas switching elements for image display devices is desired.

A liquid crystal display device is known as an example of the imagedisplay devices. Compared to passive matrix liquid crystal displaydevices, high-definition images can be obtained with active matrixliquid crystal display devices; therefore, the active matrix liquidcrystal display devices have become widely used. In the active matrixliquid crystal display devices, when pixel electrodes arranged in matrixare driven, a display pattern is formed on a screen. In more detail,when voltage is applied between a selected pixel electrode and a counterelectrode that corresponds to the selected pixel electrode, a liquidcrystal layer provided between the pixel electrode and the counterelectrode is optically modulated, and this optical modulation isrecognized as a display pattern by a viewer.

The application range of such active matrix electro-optical devices isexpanding, and demands for high-definition, a higher aperture ratio, andhigh reliability are increasing as a screen size gets larger. At thesame time, demands for improvement in productivity and cost reductionare increasing.

The cost for materials is increased as the size of the panel getslarger. In particular, a liquid crystal material provided between apixel electrode and a counter electrode is expensive.

In the case of using a liquid crystal injection method, sealing ofliquid crystal requires a complex process such as drawing of a sealant,attachment of a counter substrate, division of substrates, injection ofliquid crystal, and sealing of an inlet for injecting liquid crystal. Inparticular, as a panel size gets larger, it becomes difficult to fill aregion surrounded by the sealant (including at least a pixel portion)with liquid crystal since liquid crystal is injected using a capillaryphenomenon. When liquid crystal is injected using a capillaryphenomenon, a larger amount of liquid crystal than that to be injectedfrom the liquid crystal inlet is used in vain.

Further, when a liquid crystal injection method is used, two substratesare attached to each other and divided, and then, a liquid crystalmaterial is injected from a liquid crystal inlet formed on the dividedsurface. At this time, a path of the liquid crystal material extendingfrom the liquid crystal inlet to a pixel portion is also filled with theliquid crystal. Further, when a driver circuit portion and a pixelportion are provided over one substrate, not only the pixel portion butalso a region overlapping with the driver circuit portion is filled withthe liquid crystal in some cases. In such a manner, a region except theregion to be a display portion is also filled with the liquid crystalmaterial.

In addition, an extremely large amount of liquid crystal flows in thepath of the liquid crystal material extending from the liquid crystalinlet to the pixel portion especially around the liquid crystal inlet,compared to other portions in the panel. Therefore, there is a concernthat around the inlet, the surface of an alignment film is changed dueto friction caused by injecting the liquid crystal, and orientation ofliquid crystal molecules is disordered as a result.

Further, in a liquid crystal injection method, a step of sealing theliquid crystal inlet is necessary after the liquid crystal injection.

The present applicant propose a technique of attaching a pair ofsubstrates to each other under reduced pressure after dripping liquidcrystal in Reference 1 (U.S. Pat. No. 4,691,995).

SUMMARY OF THE INVENTION

The technique disclosed in Reference 1 is called a liquid crystaldripping method (ODF: one drop fill). A liquid crystal dripping methodcan eliminate the loss of materials because only a necessary amount ofliquid crystal is dripped to a necessary portion. Since a seal patternhas a closed loop shape, a seal pattern for a liquid crystal inlet and apath is not necessary. Accordingly, defects caused at the time of liquidcrystal injection (such as defective orientation) can be eliminated.

A liquid crystal dripping method is greatly different from a liquidcrystal injection method in the order of steps.

Manufacturing steps of a liquid crystal display device using a liquidcrystal injection method will be described. First, a sealant is drawn ona counter substrate by a screen printing method or using a dispenserapparatus. Next, the counter substrate is attached to another substrate,and the both substrates are bonded to each other by curing the sealantwith heat press. Then, the pair of substrates are divided so that partof the sealant (a liquid crystal inlet) is positioned at the edge of thesubstrate. After that, the pair of substrates are disposed in a chamberunder reduced pressure, the pressure in the chamber is made to returngradually from the reduced pressure to the atmospheric pressure with aliquid crystal material being in contact with the liquid crystal inlet,so that the liquid crystal material is injected from the liquid crystalinlet using a capillary phenomenon. The liquid crystal inlet is sealedwith a sealing material, and the sealing material is cured by beingirradiated with ultraviolet light. Finally, heat treatment is performedto align the liquid crystal molecules.

Manufacturing steps of a liquid crystal display device using a liquidcrystal dripping method will be described. First, a sealant having aclosed pattern is drawn on a counter substrate using a dispenserapparatus. Next, only a desired amount of liquid crystal is dripped to aregion surrounded by the sealant of the counter substrate. The countersubstrate is attached to another substrate under reduced pressure. Anatmosphere around the pair of substrates is changed from the reducedpressure to the atmospheric pressure. The sealant is cured by beingirradiated with ultraviolet light. Then, heat treatment for furthercuring the sealant and heat treatment for aligning the liquid crystalmolecules are performed at the same time. Finally, the pair ofsubstrates are divided.

In a liquid crystal injection method, the pair of substrates are bondedto each other by heat press and divided, and then, the liquid crystal isinjected. In a liquid crystal dripping method, the liquid crystal isdripped to the substrate, and then, the pair of substrates are attachedto each other under reduced pressure and divided.

It is necessary to perform heat treatment to align the liquid crystalmolecules. In a liquid crystal injection method, heat treatment isperformed to align the liquid crystal molecules after curing the sealingmaterial. In a liquid crystal dripping method, heat treatment for curingthe sealant and heat treatment for aligning the liquid crystal moleculesare performed at the same time, whereby a liquid crystal display deviceis efficiently manufactured.

However, when a liquid crystal dripping method is used, the orientationof the liquid crystal molecules is disordered by division of thesubstrates, which results in lower image quality of the liquid crystaldisplay device. Therefore, it is an object of the present invention toprevent the orientation of the liquid crystal molecules from beingdisordered due to division of the substrates even if a liquid crystaldripping method is used.

In addition, in order to achieve improvement in productivity and lowcost of a liquid crystal display device, it is preferable to manufacturea plurality of panels from one substrate which is 1 m on one side formass production.

The present invention provides a method for manufacturing a plurality ofliquid crystal display devices efficiently from one large-area substratehaving a size of, for example, 320 mm×400 mm, 370 mm×470 mm, 550 mm×650mm, 600 mm×720 mm, 680 mm×880 mm, 1000 mm×1200 mm, 1100 mm×1250 mm, or1150 mm×1300 mm. The present invention further provides a method formanufacturing a liquid crystal display device suitable for massproduction using a large-area substrate having a size of 1500 mm×1800mm, 1800 mm×2000 mm, 2000 mm×2100 mm, 2200 mm×2600 mm, 2600 mm×3100 mm,or the like.

In a liquid crystal dripping method, the sealant is cured at differenttiming from that in a liquid crystal injection method; thus, a differentmaterial from that used in a liquid crystal injection method is used asthe sealant. In a liquid crystal injection method, a sealant which iscured by heat press, and an ultraviolet curing resin as a sealingmaterial with which the inlet is sealed after liquid crystal injectionare used. Meanwhile, in a liquid crystal dripping method, a sealantwhich is cured by performing heat treatment after irradiation withultraviolet light is used.

In a liquid crystal injection method, the sealant which is cured by heatpress and the liquid crystal are in contact with each other, while in aliquid crystal dripping method, the sealant which is not cured and theliquid crystal are in contact with each other. Therefore, in the case ofusing a liquid crystal dripping method, it is preferable to select asealant which does not adversely affect the liquid crystal even if thesealant which is not cured and the liquid crystal are in contact witheach other. Thus, it is another object of the present invention toprovide a method for manufacturing a liquid crystal display device whichdoes not adversely affect the liquid crystal even if the sealant whichis not cured and the liquid crystal are in contact with each other.

The present inventors consider that the orientation of the liquidcrystal molecules is disordered by division of the substrates in thecase of using a liquid crystal dripping method because shearing force ishigh in a dividing step after heat treatment for aligning the liquidcrystal molecules. In a conventional dividing step, scribing isperformed using a scribing apparatus, and then, the substrates aredivided by applying impact using a breaking apparatus.

Thus, in a method for manufacturing a liquid crystal display deviceusing a liquid crystal dripping method, before attachment of a pair ofsubstrates under reduced pressure, a scribe groove is provided for atleast one of the pair of substrates with a diamond cutter or the like.This scribe groove is provided so as to have a cutting depth such thatthe substrate is not divided by being transferred or due to its weight.After the scribing, the pair of substrates are attached to each otherunder reduced pressure, heat treatment for curing a sealant and aligningthe liquid crystal molecules is performed, and then, the substrates aredivided by applying impact using a breaking apparatus. Since thescribing is performed in advance, the substrates can be divided with lowpressing force. Therefore, by performing the scribing before attachmentof the substrates, the orientation of the liquid crystal molecules canbe prevented from being disordered when the substrates are divided.

According to one aspect of the present invention disclosed in thisspecification, a method for manufacturing a liquid crystal displaydevice includes the steps of: forming a sealant over one of a pair ofsubstrates; dripping liquid crystal to a region surrounded by thesealant; providing a cutting depth for at least one of the pair ofsubstrates before attaching the pair of substrates to each other;attaching the pair of substrates to each other under reduced pressure;and dividing the pair of substrates along a band-like region providedwith the cutting depth after attaching the pair of substrates to eachother.

The present invention solves at least one of the above problems.

When a liquid crystal dripping method is used, since a sealant which isnot cured and liquid crystal are in contact with each other, it ispreferable to remove a gas component contained in the sealant bydisposing the substrate in an atmosphere under reduced pressureimmediately after drawing of the sealant. Note that the gas componentcontained in the sealant includes at least a gas generated from asolvent of the sealant and moisture contained in the sealant.

According to another aspect of the present invention disclosed in thisspecification, a method for manufacturing a liquid crystal displaydevice includes the steps of: forming a sealant over one of a pair ofsubstrates; removing a gas component from the sealant by providing thesubstrate provided with the sealant under first reduced pressure;providing a cutting depth for at least one of the pair of substratesbefore attaching the pair of substrates to each other; attaching thepair of substrates to each other under second reduced pressure which isdifferent from the first reduced pressure; and dividing the pair ofsubstrates along a band-like region provided with the cutting depthafter attaching the pair of substrates to each other.

Further, in order to prevent a gas component from generating by thedegree of vacuum when the substrates are later attached to each other,it is preferable to set the degree of vacuum in degassing after thesealant is drawn to be higher than that when the substrates are attachedto each other.

In a liquid crystal injection method, heat press is performed.Therefore, when scribing is performed before attaching a pair ofsubstrates to each other, there is a concern that the substrate isdivided by pressure in attachment, and it is difficult to apply evenpressure to the substrate, which results in uneven gaps between thesubstrates.

In the case of using a liquid crystal dripping method, even if scribingis performed before attaching a pair of substrates to each other, a stepof applying pressure to the substrate is not performed before a step ofdivision of the substrates. Although pressure is applied to part of thesubstrate when the atmosphere is changed from reduced pressure toatmospheric pressure after attachment, this part is included in a regionsurrounded by the sealant having a closed pattern of the substrate,which does not lead to division of the substrate. Needless to say, whenthe pair of substrates are attached to each other under reduced pressureafter the scribing, the sealant can be cured without any problems, sothat a sufficient adhering property of the sealant, e.g., a sealstrength of 200 N/cm² or more can be obtained.

When the substrate is moved, for example, the substrate is transferredor alignment of the substrate is performed, some power is applied fromthe outside, and the substrate can be divided. In order to prevent this,before or after the scribing, an adhesive sheet, tape, or the like maybe attached to the band-like region to which the scribing is performed,so that broken pieces of the substrate are not scattered. The tape maybe attached to the band-like region on the surface to which the scribingis performed or the surface to which the scribing is not performed. Notethat the tape is attached temporarily in this case and can be peeled offafter dividing the substrate. By use of the tape, broken pieces of thesubstrate can be prevented from being scattered in a transfer chamber orattachment equipment.

The scribing is performed so as to provide a cutting depth such that thesubstrate is not divided by being transferred or its weight. The cuttingdepth d depends on a material, a thickness, or the like of thesubstrate. For example, when a glass substrate with a thickness of 0.7mm is used, the cutting depth is preferably 0.2 mm or more and less than0.5 mm. With a cutting depth of less than 0.2 mm, power applied individing the substrate by a breaking apparatus is increased; thus, thereis a concern that the orientation of the liquid crystal molecules isdisordered. With a cutting depth of 0.5 mm or more, since the scribingis performed by fixing the substrate with a vacuum chuck, the substrateis broken when the vacuum chuck is turned off after the scribing even ifthe substrate is not divided immediately after the scribing. Therefore,when the thickness of the substrate is set to be X, the cutting depth dis set to be two-sevenths or more and less than five-sevenths of thethickness X of the substrate. The cutting depth also depends on the typeof the blade of a cutter, or pressure of a cutter; therefore, thecutting depth is preferably adjusted by a scribing apparatus asappropriate to have the most suitable value. The thickness X of a glasssubstrate that is used can be thinned in advance by grinding-polishingequipment. For example, a glass substrate with a thickness of 0.5 mm canbe thinned to 0.25 mm. Therefore, the thickness X of the substratebefore the scribing is in the range of 0.25 to 2.5 mm, inclusive.

As long as a groove which does not divide the substrate can be formed incutting, a scribing apparatus using laser light may also be used, notlimited to the scribing apparatus using a diamond cutter.

There is no particular limitation on the foregoing liquid crystaldisplay device, and a liquid crystal display device using TN liquidcrystal, IPS liquid crystal, OCB liquid crystal, STN liquid crystal, VAliquid crystal, ECB liquid crystal, GH liquid crystal, polymer dispersedliquid crystal, discotic liquid crystal, or the like can be used. Amongthem, a normally black liquid crystal panel, such as a transmissiveliquid crystal display device utilizing a vertical alignment (VA) modeis preferable. Some examples are given as a vertical alignment mode. Forexample, an MVA (multi-domain vertical alignment) mode, a PVA (patternedvertical alignment) mode, or an ASV mode can be employed. Specifically,one pixel is divided into a plurality of sub-pixels and a projectingportion is provided in a position of a counter substrate correspondingto the center of each sub-pixel, so that a multi-domain pixel is formed.Note that the projecting portion may be provided on either the countersubstrate or the element substrate, or both of them. The projectingportion makes liquid crystal molecules align radially and improvescontrollability of the alignment.

Further, an electrode for driving liquid crystal, that is, a pixelelectrode may have a top view shape like a comb-shape or a zigzaggedshape so that a direction in which voltage is applied may be varied.Alternatively, a multi-domain pixel may be formed utilizingphoto-alignment.

As an active element connected to the pixel electrode, a two-terminalactive element such as a diode, an MIM, or a ZnO varistor, or athree-terminal active element such as an amorphous TFT or a polysiliconTFT can be used.

The method as described above is about not only a matter of design. Thepresent inventors invented the method as a result of carefulexamination, by forming a liquid crystal panel using substrateattachment equipment which performs attachment of substrates underreduced pressure, manufacturing a display device using the liquidcrystal panel, and displaying images with the display device.

It is possible to prevent orientation of liquid crystal molecules frombeing disordered due to division of substrates even when a liquidcrystal dripping method is used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show examples of a manufacturing flow.

FIGS. 2A to 2G are cross-sectional views illustrating manufacturingsteps of an LCD.

FIGS. 3A and 3C are perspective views and FIG. 3B is a cross-sectionalview each illustrating part of manufacturing steps.

FIG. 4 shows an example of a manufacturing flow.

FIG. 5 is a cross-sectional structural view illustrating an activematrix liquid crystal display device.

FIGS. 6A and 6B are top views of liquid crystal modules.

FIGS. 7A to 7H illustrate examples of electronic devices.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiment modes of the present invention will be describedwith reference to the accompanying drawings. Note that the presentinvention is not limited to the following description, and modes anddetails thereof can be modified in various ways without departing fromthe spirit and the scope of the invention. Therefore, the presentinvention should not be interpreted as being limited to the followingdescription of the embodiment modes.

Embodiment Mode 1

This embodiment mode will describe an example of drawing of a sealantand dripping of liquid crystal on a counter substrate. The flow ofpanel-manufacturing will be described hereinafter. FIGS. 1A and 1B areflow charts of main manufacturing steps. In addition, FIGS. 2A to 2G arecross-sectional views illustrating the manufacturing steps.

First, a second substrate 120 used as a counter substrate and a firstsubstrate 110 provided with a TFT (not shown in the drawings) in advanceare prepared. The first substrate 110 and the second substrate 120 arenot limited to particular substrates as long as they are substrateshaving a light-transmitting property, but a glass substrate is typicallyused. In this embodiment mode, a glass substrate with a thickness of 0.7mm is used. Note that the TFT may be any of a TFT using polysilicon asan active layer (also referred to as a polysilicon TFT), a TFT usingamorphous silicon as an active layer (also referred to as an amorphoussilicon TFT), and a TFT using an organic semiconductor material as anactive layer (also referred to as an organic TFT).

Next, a counter electrode 122 formed of a transparent conductive film isformed over the second substrate 120 (FIG. 2A). In addition, alignmentfilms (not shown in the drawings) are formed for both the substrates andrubbing treatment is performed thereto, if necessary.

Next, a sealant 112 is drawn on the second substrate 120. The sealant112 is drawn by a screen printing method or by using an ink-jetapparatus or a dispenser apparatus. This drawing of the sealantcorresponds to a first step S101 in the flow chart of FIG. 1A. Thesealant may be formed for either the first substrate 110 or the secondsubstrate 120, or both of them. The sealant 112 may be an acrylicphoto-curing resin or the like. As the sealant 112, a sealant containingfiller (with a diameter of 6 to 24 μm) and having a viscosity of 40 to400 Pa·s is used. Note that a seal material which does not dissolve inliquid crystal which is in contact therewith later is preferablyselected. This sealant 112 is formed into a closed loop shape andsurrounds the counter electrode 122 (FIG. 2B).

Then, scribing is performed to the second substrate 120. This scribingto the substrate corresponds to a second step S102 in the flow chart ofFIG. 1A. Scribing may be performed to either the first substrate 110 orthe second substrate 120, or a scribe groove may be formed for both thesubstrates. Further, scribing may be performed to either the top surfaceor the bottom surface, or both the top and bottom surfaces of onesubstrate. Scribing is performed by using a scribing apparatus having adiamond cutter or the like. As illustrated in FIG. 2C, a scribe groovewith a cutting depth d is formed on one surface of the substrate.

Table 1 shows a relation between a cutting depth d that is obtained andpressure of a cutter (kgf/cm²), when scribing is performed to a glasssubstrate with a thickness of 0.7 mm and conditions of pressure of acutter and the like are made varied so that cutting depths D of thescribing apparatus are set to be 0.1, 0.2, 0.3, 0.4, and 0.5 mm.Further, it is evaluated whether the value of the cutting depth d issuitable for a manufacturing method in this embodiment mode.

TABLE 1 pressure of a cutter (kgf/cm2) cutting depth:d (mm) evaluation 00.13 x 0.1 0.27 Δ 0.1 0.35 ∘ 0.2 0.46 ∘ 0.2 0.52 x

As shown in Table 1, the cutting depth d of 0.13 mm is unsuitable (X)for the present invention because a value of pressure in dividing thesubstrate by pressure application is relatively high. The cutting depthd of 0.27 mm can reduce the value of pressure in dividing the substrateby pressure application, but there is a concern that orientation ofliquid crystal molecules is disordered depending on the gap between thesubstrates or an orientation condition of the liquid crystal molecules.The cutting depth d of 0.52 mm divides the substrate easily even whenonly a small amount of power is applied, for example, when the substrateis transferred. Thus, the cutting depth d of 0.52 mm is unsuitable (X)for the present invention. According to Table 1, it is preferable to setthe cutting depth D of the scribing apparatus to be 0.2 mm or more andless than 0.5 mm, more preferably, 0.3 mm or more and less than 0.5 mm.

Next, liquid crystal is dripped to the second substrate 120. An ink-jetapparatus or a dispenser apparatus is used for dripping of the liquidcrystal. This dripping of the liquid crystal to the substratecorresponds to a third step S103 in the flow chart of FIG. 1A. Theliquid crystal may be dripped to either the first substrate 110 or thesecond substrate 120, or both of them. As illustrated in FIG. 2D, liquidcrystal 114 is dripped to a region surrounded by the sealant 112 by useof a liquid crystal dispenser 118 under atmospheric pressure. As theliquid crystal 114, a known liquid crystal material having viscositywhich enables the liquid crystal to be dripped may be used. By use ofthe liquid crystal dispenser, only the necessary amount of the liquidcrystal 114 can be held in the region surrounded by the sealant 112without the loss of the liquid crystal. Alternatively, the liquidcrystal may be dripped by an ink-jet method.

Then, the pair of substrates are attached to each other under reducedpressure. This attachment under reduced pressure corresponds to a fourthstep S104 in the flow chart of FIG. 1A. The first substrate 110 isprovided with a pixel electrode 111, a terminal electrode 113, and acolumnar spacer 115 in advance. The first substrate 110 which isprovided with a pixel portion having the pixel electrode 111 and thesecond substrate 120 which is provided with the counter electrode 122,the alignment film, and/or the like are attached to each other underreduced pressure so that bubbles do not enter a gap between them (FIG.2E).

Then, the sealant is irradiated with ultraviolet light. This irradiationof the sealant with ultraviolet light corresponds to a fifth step S105in the flow chart of FIG. 1A.

After that, heat treatment is performed to further cure the sealant 112.At the same time, the liquid crystal is also heated, so that the liquidcrystal molecules are aligned. This heat treatment to the sealant or theliquid crystal corresponds to a sixth step S106 in the flow chart ofFIG. 1A. By this heat treatment, the gap between the substrates isfixed. As illustrated in FIG. 2F, the gap between the substrates is heldby the columnar spacer 115.

Although the sealant is cured by the heat treatment after theirradiation with ultraviolet light, the present invention is not limitedthereto, and an acrylic thermosetting resin may used as the sealant aslong as a sufficient adhering property of the sealant, e.g., a sealstrength of 200 N/cm² or more, can be obtained.

Next, the substrate is divided as illustrated in FIG. 2G. This divisionof the substrate corresponds to a seventh step S107 in the flow chart ofFIG. 1A. Pressure is applied along a scribe line which is a continuousscribe groove, and the substrate is divided, whereby the terminalelectrode 113 is exposed. Since the scribe line is formed in advance,part of the second substrate can be divided with low power. Therefore,even if the substrate is divided after the heat treatment for aligningthe liquid crystal molecules, the orientation of the liquid crystalmolecules can be prevented from being disordered.

The TN liquid crystal display device is described as an example in thisembodiment mode. In the case of the IPS liquid crystal display device,the counter electrode is not provided for the counter substrate.

FIG. 1A shows the flow of manufacturing in which scribing is performedto the substrate after the sealant is drawn. However, the presentinvention is not limited thereto as long as scribing is performed beforeattachment of the substrates under reduced pressure. As shown in FIG.1B, the sealant may be drawn after scribing is performed to thesubstrate. In that case, a first step S201 corresponds to the scribingto the substrate, a second step S202 corresponds to the drawing of thesealant, a third step S203 corresponds to the dripping of the liquidcrystal, a fourth step S204 corresponds to the attachment of thesubstrates under reduced pressure, a fifth step S205 corresponds to theirradiation of the sealant with ultraviolet light, a sixth step S206corresponds to the heat treatment to the sealant or the liquid crystal,and a seventh step 207 corresponds to the division of the substrate.

Embodiment Mode 2

This embodiment mode will describe an example of a method in which aplurality of panels are manufactured from one substrate.

As a substrate 310 illustrated in FIG. 3A, a quartz substrate with athickness of 1.1 mm is used. A pixel portion 311 having a pixelelectrode is formed over the substrate 310. This embodiment mode showsan example in which four pixel portions 311 are formed.

A scribe groove 313 is formed using a diamond cutter or laser light. Thescribe groove is formed so as to separate the pixel portions 311. In thecase of using the quartz substrate, the cutting depth d is more than 0.3mm and 0.7 mm or less, and preferably about 0.6 mm here. Since thequartz substrate is harder than a glass substrate, the quartz substrateis broken only by scribing, when pressure of a cutter is increased toform a scribe groove with a cutting depth of over 0.7 mm. In addition,when the cutting depth d is 0.3 mm or less, it is difficult to dividethe substrate unless power for division is increased.

Next, a sealant 312 is formed to surround the pixel portion 311. Thesealant 312 has a closed pattern and is formed between the peripheraledge of the pixel portion 311 and the edge of the substrate 310, orbetween the scribe groove 313 and the peripheral edge of the pixelportion 311.

FIG. 3B is a cross-sectional view during formation of a liquid crystallayer using a liquid crystal dispenser 318. A liquid crystal material314 is dripped or discharged from the liquid crystal dispenser 318 sothat the pixel portion 311 surrounded by the sealant 312 is covered. Theliquid crystal dispenser 318 may be moved, or the liquid crystaldispenser 318 may be fixed and the substrate may be moved to form theliquid crystal layer. Further, a plurality of the liquid crystaldispensers 318 may be provided in one treatment chamber, so that theliquid crystal may be dripped to plural parts of one substrate at onetime.

In addition, FIG. 3C is a perspective view after formation of the liquidcrystal layer. The liquid crystal material 314 is dripped or dischargedto the regions surrounded by the sealants 312 as selected.

Then, another substrate is attached to the substrate 310 under reducedpressure. Finally, the substrates are divided and four panels aremanufactured. Since the scribe groove is provided in advance before thesubstrates are attached to each other, the substrates after beingattached to each other can be divided with relatively low power.Therefore, disorder of the orientation of the liquid crystal moleculeswhich is due to pressure applied in dividing the attached substrates canbe suppressed.

In particular, when a plurality of panels are manufactured from onesubstrate, the distance between the adjacent pixel portions ispreferably shortened in order to manufacture a plurality of panels fromone substrate efficiently. In addition, when the distance between theadjacent sealants is short, it is difficult to divide the substrates;therefore, high pressure is applied to divide the substrates.Accordingly, since the distance between the scribe groove and thesealant and the distance between the scribe groove and the liquidcrystal layer are shortened, the present invention is very effective,which reduces the pressure applied in dividing the substrates byproviding the scribe groove in advance before the substrates areattached to each other.

Although this embodiment mode shows an example in which, after thesealant and the liquid crystal layer are formed over the substratehaving the pixel portion, the substrate having the pixel portion isattached to another substrate, that is, the counter substrate, thepresent invention is not limited thereto; the sealant and the liquidcrystal layer may be provided for the counter substrate as in EmbodimentMode 1.

This embodiment mode can be freely combined with Embodiment Mode 1. Forexample, the sealant and the scribe groove may be formed for thesubstrate having the pixel portion, the sealant and the scribe groovemay also be formed for the counter substrate, the pair of substrates maybe attached to each other under reduced pressure, and then, thesubstrates may be divided. In this case, since the scribe grooves areformed for the both substrates in advance, the both substrates can bedivided by one dividing treatment.

Embodiment Mode 3

This embodiment mode will describe an example in which degassingtreatment of a sealant is performed under reduced pressure with a higherdegree of vacuum than in the case of attaching substrates to each other.

First, a sealant is drawn on a substrate. This drawing of the sealantcorresponds to a first step S401 in the flow chart of FIG. 4. Aphoto-curing resin is used as the sealant. As the sealant, a materialwhich is cured efficiently by performing heat treatment afterirradiation with ultraviolet light is used. When a liquid crystaldripping method is used, the sealant is cured and the liquid crystalmolecules are aligned by performing irradiation with ultraviolet lightand heat treatment in this order after the substrates are attached toeach other; therefore, the order of the irradiation with ultravioletlight and the heat treatment is important. Such a sealant is not easilypolymerized when being subjected to the heat treatment and thenirradiated with ultraviolet light, and there is a concern that itbecomes difficult to obtain a desired seal strength.

Next, degassing of the sealant is performed under first reduced pressure(e.g., a degree of vacuum is 10⁻⁵ to 10⁻⁶ Pa) and the surface of thesealant to be in contact with liquid crystal which is dripped later isdried. Accordingly, adverse effect due to contact of the sealant and theliquid crystal can be reduced. The degassing of the sealant under thefirst reduced pressure corresponds to a second step S402 in the flowchart of FIG. 4. In the case of using a liquid crystal dripping method,since the sealant which is not cured and the liquid crystal are incontact with each other, it is preferable to remove a gas componentcontained in the sealant by disposing the substrate in an atmosphereunder reduced pressure immediately after the drawing of the sealant.Note that it is preferable to dispose the substrate in an atmosphereunder reduced pressure without performing heating which cures thesealant.

Further, in order to prevent a gas component from generating by thedegree of vacuum when the substrates are later attached to each other,it is preferable to set the degree of vacuum in degassing after thesealant is drawn to be higher than that when the substrates are attachedto each other.

Next, scribing is performed to at least one of the pair of substrates.This scribing to the substrate corresponds to a third step S403 in theflow chart of FIG. 4.

Next, liquid crystal is dripped to the substrate. This dripping of theliquid crystal to the substrate corresponds to a fourth step S404 in theflow chart of FIG. 4. The liquid crystal may be dripped to at least oneof the pair of substrates. The liquid crystal is dripped to a regionsurrounded by the sealant by a liquid crystal dispenser underatmospheric pressure. As the liquid crystal, a known liquid crystalmaterial having viscosity which enables the liquid crystal to be drippedmay be used. By the liquid crystal dispenser, only the necessary amountof the liquid crystal can be held in the region surrounded by thesealant without the loss of the liquid crystal.

Then, the pair of substrates are attached to each other under secondreduced pressure. This attachment of the substrates under the secondreduced pressure corresponds to a fifth step S405 in the flow chart ofFIG. 4. Since degassing of the sealant is performed under the firstreduced pressure in advance, a gas can be prevented from being releasedfrom the sealant during the attachment of the substrates.

Then, the sealant is irradiated with ultraviolet light. This irradiationof the sealant with ultraviolet light corresponds to a sixth step S406in the flow chart of FIG. 4.

After that, heat treatment is performed to further cure the sealant. Atthe same time, the liquid crystal is also heated, so that the liquidcrystal molecules are aligned. This heat treatment to the sealant or theliquid crystal corresponds to a seventh step S407 in the flow chart ofFIG. 4. By this heat treatment, the gap between the substrates is fixed.

Next, the substrate is divided. This division of the substratecorresponds to an eighth step S408 in the flow chart of FIG. 4. Pressureis applied along a scribe line which is a continuous scribe groove, andthe substrate is divided. Since the scribe line is formed in advance,the substrate can be divided with low power. Therefore, even if thesubstrate is divided after the heat treatment for aligning the liquidcrystal molecules, the orientation of the liquid crystal molecules canbe prevented from being disordered.

In the case of using a liquid crystal dripping method, since the sealantwhich is not cured and the liquid crystal are in contact with eachother, it is preferable to remove a gas component contained in thesealant by disposing the substrate in an atmosphere under reducedpressure immediately after the drawing of the sealant. The gas componentcontained in the sealant includes at least a gas generated from asolvent of the sealant and moisture contained in the sealant.

Another structure of the present invention disclosed in thisspecification is a method for manufacturing a liquid crystal displaydevice including: forming a sealant for one of a pair of substrates,removing a gas component from the sealant by disposing the substrateprovided with the sealant under first reduced pressure, providing acutting depth for at least one of the substrates before the pair ofsubstrates are attached to each other, attaching the pair of substratesto each other under second reduced pressure which is different from thefirst reduced pressure, and dividing the pair of substrates along aband-like region provided with the cutting depth after attaching thesubstrates to each other.

Further, in order to prevent a gas component from generating by thedegree of vacuum when the substrates are later attached to each other,it is preferable to set the degree of vacuum in degassing after thesealant is drawn to be higher than that when the substrates are attachedto each other.

Through the above process, a method for manufacturing a liquid crystaldisplay device can be provided, in which liquid crystal is not adverselyaffected even when a sealant which is not cured and liquid crystal arein contact with each other. Further, the orientation of the liquidcrystal molecules can be prevented from being disordered by pressurewhich is applied in dividing the attached substrates.

This embodiment mode can be freely combined with Embodiment Mode 1 or 2.For example, as shown in the flow chart of FIG. 1B, the sealant may bedrawn after scribing is performed to the substrate.

The present invention having the above structure will be morespecifically explained with embodiments described hereinafter.

Embodiment 1

This embodiment will describe a manufacturing process of an activematrix liquid crystal display device with reference to FIG. 5.

First, an active matrix substrate is manufactured using a substrate 600having a light-transmitting property. The manufacturing cost ispreferably reduced by using a large-area substrate having a size of, forexample, 600 mm×720 mm, 680 mm×880 mm, 1000 mm×1200 mm, 1100 mm×1250 mm,1150 mm×1300 mm, 1500 mm×1800 mm, 1800 mm×2000 mm, 2000 mm×2100 mm, 2200mm×2600 mm, or 2600 mm×3100 mm. As for the substrate, a glass substratemade of barium borosilicate glass, aluminoborosilicate glass, or thelike typified by Corning 7059 glass, 1737 glass, or the likemanufactured by Corning Incorporated can be used. As another example ofthe substrate, a light-transmitting substrate such as a quartz substratecan be used. First, a conductive layer is formed over the entire surfaceof the substrate 600 having an insulating surface by a sputteringmethod. After that, a resist mask is formed by a first photolithographystep, and an unnecessary portion is removed by etching to form a wireand an electrode (such as a gate electrode, a storage capacitor wire,and a terminal). Note that a base insulating film is formed over thesubstrate 600 if necessary.

The wire and the electrode are formed using an element selected fromtitanium, tantalum, tungsten, molybdenum, chromium, and neodymium, analloy containing the element as a component, or nitride containing theelement as a component. Further, two or more of elements selected fromtitanium, tantalum, tungsten, molybdenum, chromium, and neodymium, analloy containing the element as a component, and nitride containing theelement as a component may be selected and stacked.

As a screen size gets larger, the length of each wire is increased, andthe problem of an increase in wire resistance is caused, which causes anincrease in power consumption. Therefore, in order to decrease wireresistance and reduce power consumption, copper, aluminum, silver, gold,chromium, iron, nickel, platinum, or an alloy thereof can be used asmaterials of the above wire and electrode. Further, the wire and theelectrode may also be formed by an ink-jet method using an independentlydispersed ultrafine particle dispersion liquid in which ultrafineparticles (each with a grain size of 5 to 10 nm) of metal such assilver, gold, copper, or palladium are dispersed at high concentrationwithout being aggregated.

Next, a gate insulating film is formed over the entire surface by a PCVDmethod. The gate insulating film is formed using a stacked-layer of asilicon nitride film and a silicon oxide film with a thickness of 50 to200 nm, preferably 150 nm. Note that the gate insulating film is notlimited to a stacked-layer, and an insulating film such as a siliconoxide film, a silicon nitride film, a silicon oxynitride film, or atantalum oxide film can also be used.

Then, over the entire surface of the gate insulating film, a firstamorphous semiconductor film is formed with a thickness of 50 to 200 nm,preferably 100 to 150 nm by a known method such as a plasma CVD methodor a sputtering method. Typically, an amorphous silicon (a-Si) film isformed with a thickness of 100 nm. Note that since a chamber size isincreased when forming a film over a large-area substrate, it takes longprocessing time to evacuate the chamber and requires a large amount of afilm formation gas. Therefore, further cost reduction may be achieved byforming the amorphous silicon (a-Si) film using a linear plasma CVDapparatus under atmospheric pressure.

After that, a second amorphous semiconductor film containing an impurityelement imparting one conductivity type (n-type or p-type) is formedwith a thickness of 20 to 80 nm. The second amorphous semiconductor filmcontaining an impurity element imparting one conductivity type (n-typeor p-type) is formed over the entire surface by a known method such as aplasma CVD method or a sputtering method. In this embodiment, the secondamorphous semiconductor film containing an impurity element impartingn-type conductivity is formed using a silicon target to which phosphorusis added.

Next, a resist mask is formed by a second photolithography step, and anunnecessary portion is removed by etching to form a first island-shapedamorphous semiconductor film and a second island-shaped amorphoussemiconductor film. Wet etching or dry etching is used as an etchingmethod at this time.

Then, a conductive layer covering the second island-shaped amorphoussemiconductor film is formed by a sputtering method. After that, aresist mask is formed by a third photolithography step, and anunnecessary portion is removed by etching to form a wire and anelectrode (such as a source wire, a drain electrode, and a storagecapacitor electrode). The above wire and electrode are formed using anelement selected from aluminum, titanium, tantalum, tungsten,molybdenum, chromium, neodymium, copper, silver, gold, chromium, iron,nickel, and platinum, or an alloy containing the element as a component.Alternatively, the wire and the electrode may be formed by an ink-jetmethod using an independently dispersed ultrafine particle dispersionliquid in which ultrafine particles (each with a grain size of 5 to 10nm) of metal such as silver, gold, copper, or palladium are dispersed athigh concentration without being aggregated. By forming the wire and theelectrode by an ink-jet method, the photolithography step becomesunnecessary and a further cost reduction can be achieved.

Next, a resist mask is formed by a fourth photolithography step, and anunnecessary portion is removed by etching to form a source wire, a drainelectrode, and a capacitor electrode. Wet etching or dry etching is usedas an etching method at this time. At this time, a storage capacitor isformed which uses, as a dielectric, an insulating film made of the samematerial as the gate insulating film. Then, using the source wire andthe drain electrode as masks, part of the second amorphous semiconductorfilm is removed in a self-aligned manner and part of the first amorphoussemiconductor film is thinned. The thinned region serves as a channelformation region of a TFT.

Then, a first protective film made of a silicon nitride film with athickness of 150 nm and a first interlayer insulating film formed usinga silicon oxynitride film with a thickness of 150 nm are formed over theentire surface by a plasma CVD method. Note that since a chamber size isincreased when forming a film over a large-area substrate, it takes longprocessing time to evacuate the chamber and requires a large amount of afilm formation gas. Therefore, a further cost reduction may be achievedby forming the protective film made of a silicon nitride film using alinear plasma CVD apparatus under atmospheric pressure. After that,hydrogenation is performed and a channel-etched TFT is manufactured.

Although the channel-etched type is given in this embodiment as anexample of the structure of the TFT, the TFT structure is notparticularly limited thereto, and a channel stopper TFT, a top gate TFT,or a staggered TFT may be used.

A second protective film 619 is formed by an RF sputtering method. Asilicon nitride film is formed as the second protective film 619 bysputtering a single-crystalline silicon target with an N₂ gas or a mixedgas of N₂ and a rare gas under the condition that a back-pressure is setat 1×10⁻³ Pa or less by using a turbomolecular pump or a cryopump. Thisdense silicon nitride film effectively prevents variations or the likein threshold voltage which is caused by contamination of the TFT due toalkali metal or alkaline earth metal such as sodium, lithium, ormagnesium. Further, the silicon nitride film has an excellent blockingproperty against moisture or oxygen. The oxygen and hydrogen content inthe silicon nitride film is preferably set at 10 at. % or less, morepreferably 1 at. % or less in order to increase the blocking property.

Next, a resist mask is formed by a fifth photolithography step, andcontact holes which reach the drain electrode and the storage capacitorelectrode are then formed by a dry etching step. At the same time, acontact hole (not shown in the drawing) for electrically connecting thegate wire and a terminal may be formed in a terminal portion, and ametal wire (not shown in the drawing) for electrically connecting thegate wire and the terminal may be formed. In addition, at the same time,a contact hole (not shown in the drawing) which reaches the source wiremay be formed, and a metal wire connected to the source wire may beformed. A pixel electrode of ITO or the like may be formed after formingthese metal wires, or these metal wires may be formed after forming thepixel electrode of ITO or the like.

Then, a transparent conductive film is formed of an alloy of indiumoxide and tin oxide (ITO), an alloy of indium oxide and zinc oxide(In₂O₃—ZnO), zinc oxide, or the like with a thickness of 110 nm. Afterthat, a sixth photolithography step and an etching step are performed,so that a pixel electrode 601 is formed.

As described above, an active matrix substrate including the sourcewire, the inverted staggered TF of the pixel portion, the storagecapacitor, and the terminal can be manufactured by the sixphotolithography steps.

Then, an alignment film 623 is formed over the active matrix substrateand rubbing treatment is performed thereto. Note that before formationof the alignment film 623, a columnar spacer 602 is formed at thedesired position in order to keep a gap between the substrates bypatterning an organic resin film such as an acrylic resin film in thisembodiment. Alternatively, spherical spacers may be dispersed over theentire surface of the substrate instead of the columnar spacer.

Then, a counter substrate is prepared. This counter substrate isprovided with a color filter 620 in which a colored layer and alight-blocking layer are arranged for each pixel. In addition, aplanarizing film is provided to cover the color filter and thelight-blocking layer. Then, a counter electrode 621 is formed over theplanarizing film using a transparent conductive film in a positionoverlapping with the pixel portion. Then, an alignment film 622 isformed over the entire surface of the counter substrate and rubbingtreatment is performed thereto.

Next, a sealant 607 is drawn so as to surround the pixel portion of theactive matrix substrate in accordance with Embodiment Mode 1. Afterthat, scribing is performed, so that a scribe groove with a cuttingdepth d is formed. Liquid crystal is dripped to the region surrounded bythe sealant 607 by a liquid crystal dispenser. Then, the active matrixsubstrate and the counter substrate are attached to each other underreduced pressure with the sealant 607 to seal a liquid crystal layer624. The sealant 607 is mixed with filler (not illustrated), so that twosubstrates can be attached to each other with a uniform gap therebetweenby the filler and the spacer 602. By using a liquid crystal drippingmethod, the amount of liquid crystal used in the manufacturing processcan be reduced, and particularly when a large-area substrate is used,the manufacturing cost can be drastically reduced.

Then, the active matrix substrate or the counter substrate is dividedinto a desired shape. Since the scribe groove is formed in advance, thesubstrate can be divided with pressure in a range such that theorientation of liquid crystal molecules is not disordered. In such amanner, the active matrix liquid crystal display device is completed.

Furthermore, optical films such as a polarizing plate 603 and a colorfilter are provided as appropriated using a known technique. Then, anFPC is attached using a known technique.

The liquid crystal module obtained through the above steps is providedwith a backlight 604 and a light guiding plate 605 and covered with acover 606, whereby the active matrix liquid crystal display device(transmissive type) is completed, a partial cross-sectional view ofwhich is illustrated in FIG. 5. Note that the cover and the liquidcrystal module are fixed to each other using an adhesive or an organicresin. In addition, since the liquid crystal display device is oftransmissive type, the polarizing plate 603 is attached to each of theactive matrix substrate and the counter substrate.

Further, an example of the transmissive type is described in thisembodiment; however, the liquid crystal display device is not limitedthereto, and a reflective or semi-transmissive liquid crystal displaydevice can also be manufactured. In the case of obtaining a reflectiveliquid crystal display device, a metal film with high opticalreflectance, typically, a film containing aluminum or silver as its maincomponent, a stacked-layer thereof, or the like may be used for a pixelelectrode.

This embodiment can be freely combined with Embodiment Mode 1, 2, or 3.

Embodiment 2

In this embodiment, a top view of the liquid crystal module obtained inEmbodiment 1 is illustrated in FIG. 6A, and a top view of a liquidcrystal module different from that of Embodiment 1 is illustrated inFIG. 6B.

The TFT whose active layer is formed using an amorphous semiconductorfilm described in Embodiment 1 has low field-effect mobility,approximately only about 1 cm²/Vsec. Therefore, a driver circuit forperforming image display is formed as an IC chip and mounted by a TAB(tape automated bonding) method or a COG (chip on glass) method.

In FIG. 6A, reference numeral 701 denotes an active matrix substrate;706, a counter substrate; 704, a pixel portion; 707, a sealant; and 705,an FPC. Note that liquid crystal is dripped by a dispenser apparatus oran ink-jet apparatus under reduced pressure, and the pair of substrates701 and 706 are attached to each other with the sealant 707.

The TFT according to Embodiment 1 has low field-effect mobility, but inthe case of mass-production using large-area substrates, the cost forthe manufacturing process can be reduced since the manufacturing processis carried out at low temperature. According to the present invention,that is, when the liquid crystal is dripped by a dispenser apparatus oran ink-jet apparatus under reduced pressure and a pair of substrates areattached to each other, the liquid crystal can be held between the pairof substrates regardless of their sizes, so that a display deviceprovided with a liquid crystal panel having a large-sized screen of from20 to 80 inches can be manufactured.

When an active layer is formed using a semiconductor film which isformed by crystallizing an amorphous semiconductor film to obtain acrystalline structure by a known crystallization treatment, typically, apolysilicon film, a TFT which has high field effect mobility can beobtained, and a driver circuit having a CMOS circuit can also be formedover the same substrate as the pixel portion. Further, in addition tothe driver circuit, a CPU and the like can be manufactured over the samesubstrate as the pixel portion.

When a TFT having an active layer formed using a polysilicon film isused, a liquid crystal module as illustrated in FIG. 6B can bemanufactured.

In FIG. 6B, reference numeral 711 denotes an active matrix substrate;716, a counter substrate; 712, a source signal line driver circuit; 713,a gate signal line driver circuit; 714, a pixel portion; 717, a firstsealant; and 715, an FPC. Note that liquid crystal is dripped by adispenser apparatus or an ink-jet apparatus under reduced pressure, andthe pair of substrates 711 and 716 are attached to each other with thefirst sealant 717 and a second sealant 718. Since the liquid crystal isnot necessary for a driver circuit portion including the source signalline driver circuit 712 and the gate signal line driver circuit 713, theliquid crystal is held only in the pixel portion 714, and the secondsealant 718 is provided for reinforcement of the whole panel.

This embodiment can be freely combined with Embodiment Mode 1, 2, or 3or Embodiment 1.

Embodiment 3

Electronic devices can be manufactured by incorporating the liquidcrystal display device obtained according to the present invention intoa display portion. Examples of the electronic devices are as follows:cameras such as video cameras or digital cameras, goggle type displays(head mounted displays), navigation systems, sound reproduction devices(car audios, audio components, or the like), laptop computers, gamemachines, mobile information terminals (mobile computers, mobiletelephones, mobile game machines, electronic books, or the like), imagereproduction devices equipped with recording media (specifically, adevice which reproduces the recording medium such as a digital versatiledisc (DVD) and which is equipped with a display for displaying theimage), and the like. Specific examples of those electronic devices areillustrated in FIGS. 7A to 7H.

FIG. 7A illustrates a television which includes a casing 2001, asupporting base 2002, a display portion 2003, speaker units 2004, avideo input terminal 2005, and the like. The present invention can beapplied to the display portion 2003. Note that the term “television”includes every television for displaying information such as one for apersonal computer, one for receiving TV broadcasting, and one foradvertising.

FIG. 7B illustrates a digital camera which includes a main body 2101, adisplay portion 2102, an image receiving unit 2103, operation keys 2104,an external connection port 2105, a shutter button 2106, and the like.The present invention can be applied to the display portion 2102.

FIG. 7C illustrates a laptop personal computer which includes a mainbody 2201, a casing 2202, a display portion 2203, a keyboard 2204, anexternal connection port 2205, a pointing device 2206, and the like. Thepresent invention can be applied to the display portion 2203.

FIG. 7D illustrates a mobile computer which includes a main body 2301, adisplay portion 2302, a switch 2303, operation keys 2304, an infraredray port 2305, and the like. The present invention can be applied to thedisplay portion 2302.

FIG. 7E illustrates a portable image reproducing device equipped with arecording medium (specifically, a DVD player). The device includes amain body 2401, a casing 2402, a display portion A 2403, a displayportion B 2404, a recording medium (such as DVD) reading unit 2405,operation keys 2406, speaker units 2407, and the like. The displayportion A 2403 mainly displays image information whereas the displayportion B 2404 mainly displays text information. The present inventioncan be applied to the display portions A 2403 and B 2404. Note that theterm “image reproducing device equipped with a recording medium”includes home-use game machines and the like.

FIG. 7F illustrates a game machine which includes a main body 2501, adisplay portion 2502, operation switches 2504, and the like.

FIG. 7G illustrates a video camera which includes a main body 2601, adisplay portion 2602, a casing 2603, an external connection port 2604, aremote control receiving unit 2605, an image receiving unit 2606, abattery 2607, an audio input unit 2608, operation keys 2609, and thelike. The present invention can be applied to the display portion 2602.

FIG. 7H illustrates a mobile phone which includes a main body 2701, acasing 2702, a display portion 2703, an audio input unit 2704, an audiooutput unit 2705, operation keys 2706, an external connection port 2707,an antenna 2708, and the like. The present invention can be applied tothe display portion 2703.

As described above, the display device obtained by implementing thepresent invention may be used as the display portions of variouselectronic devices. The electronic devices of this embodiment may bemanufactured using a liquid crystal display device which uses anystructures of Embodiment Modes 1 to 3, and Embodiments 1 and 2.

According to the present invention, it becomes possible to manufacture aliquid crystal display device of which use efficiency of liquid crystalmaterials is high, and the disordered orientation of the liquid crystalmolecules is suppressed by attachment of the substrates under reducedpressure, which is suitable for manufacturing a plurality of panels fromone substrate.

This application is based on Japanese Patent Application Serial No.2007-119324 filed with Japan Patent Office on Apr. 27, 2007, the entirecontents of which are hereby incorporated by reference.

1. A method for manufacturing a liquid crystal display device,comprising the steps of: setting a cutting depth of a scribing apparatusfor scribing at least one of a pair of substrates before attaching thepair of substrates to each other; scribing at least one of the pair ofsubstrates after setting; forming a sealant over one of the pair ofsubstrates after scribing; dripping liquid crystal to a regionsurrounded by the sealant after forming the sealant; attaching the pairof substrates to each other under reduced pressure after scribing; anddividing the pair of substrates along a band-like region which is formedby the scribing.
 2. The method for manufacturing a liquid crystaldisplay device according to claim 1, wherein the pair of substrates areglass substrates or quartz substrates.
 3. The method for manufacturing aliquid crystal display device according to claim 1, wherein the cuttingdepth of the scribing apparatus is two-sevenths or more and less thanfive-sevenths of a thickness of the substrate.
 4. A method formanufacturing a liquid crystal display device, comprising the steps of:forming a groove on at least one of a pair of substrates; forming asealant over one of the pair of substrates after forming the groove;dripping liquid crystal to a region surrounded by the sealant afterforming the sealant; attaching the pair of substrates to each otherunder reduced pressure after forming the groove; and dividing the pairof substrates along the groove after attaching the pair of substrates toeach other.
 5. The method for manufacturing a liquid crystal displaydevice according to claim 4, wherein the pair of substrates are glasssubstrates or quartz substrates.
 6. The method for manufacturing aliquid crystal display device according to claim 4, wherein a depth ofthe groove is two-sevenths or more and less than five-sevenths of athickness of the substrate.